import java.io.BufferedReader;
import java.io.*;

public class work4_2 {
	public static void main(String[] args)
	throws java.io.IOException {
		int jumsu;
		char hakjum;
		String iput;
		System.out.println("***** result *****");
		System.out.print("Input jumsu: ");
		InputStreamReader kkk = new InputStreamReader(System.in);
		BufferedReader bbb = new BufferedReader(kkk);
		iput = bbb.readLine();
		jumsu = Integer.parseInt(iput);
		
		if(jumsu >= 90)
		{
			hakjum='A';
			System.out.println("Hakjum: " + hakjum);
		}
		else if(jumsu >= 80)
		{
			hakjum='B';
			System.out.println("Hakjum: " + hakjum);
		}
		else if(jumsu >= 70)
		{
			hakjum='C';
			System.out.println("Hakjum: " + hakjum);
		}	
		else if(jumsu >= 60)
		{
			hakjum='D';
			System.out.println("Hakjum: " + hakjum);
		}
		else
		{
			hakjum='F';
			System.out.println("Hakjum: " + hakjum);
		}
		
	}
}
